Geological carbon sequestration and its influence on subsurface microbial diversity an metabolic carbon cycling
| dc.contributor.advisor | Van Heerden, E. | |
| dc.contributor.advisor | Litthauer, D. | |
| dc.contributor.advisor | Onstott, T. C. | |
| dc.contributor.advisor | Phelps, T. J. | |
| dc.contributor.advisor | Surridge, T. | |
| dc.contributor.author | Erasmus, Mariana | |
| dc.date.accessioned | 2016-11-23T13:37:27Z | |
| dc.date.available | 2016-11-23T13:37:27Z | |
| dc.date.issued | 2015-08 | |
| dc.description.abstract | English: Climate change is a reality and is a consequence of too high levels of greenhouse gases being emitted into the atmosphere, especially CO2. This is happening mainly due to the burning of fossil fuels, but other human or industrial activities are also contributing. These additional emissions are responsible for the greenhouse effect, resulting in an increase in the global average temperature of the Earth's atmosphere. Industrialization and the rise in population levels around the world has increased the demand for energy and by meeting that demand more emissions are being released into the atmosphere and are responsible for an atmospheric increase of CO2 from 280 ppm around 1850 to 400 ppm today. This is creating long term, harmful conditions on the Earth, influencing the economy, the ecology, and human health. As an attempt to manage the carbon resources more efficiently, South Africa will be storing anthropogenic CO2 in geological formations. Within these deep subsurface environments, considered for carbon sequestration, highly diverse microbial communities can be found and the metabolic activities of these microorganisms are closely tied to the geochemical and mineralogical processes occurring within the subsurface. Therefore, to determine possible influences that the CO2 could have on the diversity and metabolic carbon cycling of these subsurface microorganisms, consideration was given to the interaction between the sequestered CO2 and the subsurface biome, as well as the geological environments. In order to possibly understand how these subsurface biomes will operate in situ, the biogeochemistry for a study site, similar to proposed sites for carbon sequestration in South Africa, was characterized comprehensively. The subsurface biome from the study site, used for this research, was found to contain microorganisms belonging to the Archaeal, the Bacterial, and the Eukaryal domains, but was dominated by the Bacteria, specifically the Proteobacteria. A specifically designed, continuous high pressure bioreactor was used to evaluate the influence of the stored CO2 on the subsurface microbial diversity and metabolic carbon cycling, by mimicking carbon sequestration conditions. Due to the extreme conditions of the deep subsurface, most of these microorganisms have to grow and survive in extreme energy limiting conditions, making them likely to be inactive or to display exceptionally low metabolic activities. Even though this research indicated that in most of the conditions tested the microorganisms were not able to multiply or to produce detectable amounts of expected metabolic products; they surprisingly remained viable. The most likely reason for this was due to the presence of biofilm formations which the microorganisms used as a possible protection mechanism towards resisting the harsh conditions they were subjected to. Ultimately, this indicated that viability might be more important, than specific diversity changes or biomass yields for carbon cycling studies in the deep subsurface. A considerable decrease in the diversity was observed after the biome was subjected to carbon sequestration conditions. Only groups from the Bacteria and Archaea were able to survive these conditions, but no Eukarya could be detected. Transcriptome data obtained for the subsurface biome indicated that gene products from sulphur metabolism, nitrogen metabolism, and carbon metabolism were present and diversity analyses of the bioreactor confirmed that microorganisms, utilizing these metabolisms, remained viable after six weeks under carbon sequestration conditions. These conditions, mainly due to the acidic environment created by the dissolved CO2, allowed for significant leaching of metals from the sandstone, especially aluminium and iron, creating more stressful conditions, thus restricting the growth of the subsurface biome even more. This could result in substantial impacts on the carbon cycling occurring in the deep subsurface, and should therefore be considered during carbon sequestration. | en_ZA |
| dc.description.abstract | Afrikaans: Klimaatsverandering is ‘n werklikheid en is die gevolg van te hoë vlakke van kweekhuisgasse, veral CO2, wat in die atmosfeer uitgestraal word. Dit gebeur hoofsaaklik as gevolg van die verbranding van fossielbrandstof, maar ander menslike en industriële aktiwiteite lewer ook ‘n bydrae. Hierdie addisionele uitstralings is verantwoordelik vir die kweekhuiseffek en dit veroorsaak gevolglik ‘n toename in die totale gemiddelde temperatuur van die aarde se atmosfeer. As gevolg van industrialisering en die die toename in die bevolkingsaanwas, het die vraag na energie verhoog en om in hierdie aanvraag te voorsien, word meer uitstralings in die atmosfeer gedoen, wat dus verantwoordelik is vir ‘n toename van atmosferiese CO2 van 280 dpm rondom 1850 tot 400 dpm vandag. Dit veroorsaak langtermyn skadelike toestande op die aarde wat weer ‘n invloed het op die ekonomie, die ekologie, en ook menslike gesondheid. Suid Afrika beplan om antropogenetiese CO2 in geologiese formasies te stoor, in ‘n poging om die koolstof voorrade meer doeltreffend te bestuur. Binne in hierdie diep ondergrondse omgewings, wat oorweeg word vir koolstofberging, word hoë mikrobiese bevolkings gevind en die metabolise aktiwiteite van hierdie mikroorganismes is baie nou verbind aan die geochemiese en mineralogiese prosesse wat in die ondergrondse omgewing plaasvind. Die interaksie tussen die opgeruimde CO2 en die ondergrondse bioom, asook die geologiese omgewings was ondersoek, om te bepaal wat die gevolglike invloed mag wees wat die CO2 op die mikrobiese diversiteit en metabolise koolstofsiklus mag hê. Om te probeer verstaan hoe hierdie ondergrondse bioom in situ funksioneer, was die biogeochemie vir ‘n studieterrein, soortgelyk aan die voorgestelde omgewings vir koolstofberging in Suid Afrika, volledig ondersoek. Dit was bevind dat die ondergrondse bioom van hierdie studieterrein mikroorganismes vanuit die Archaea, die Bakterieë, en die Eukariote bevat, maar was oorheers deur die Bakterieë, veral die Proteobakterieë. Koolstofbergingstoestande is nageboots deur die gebruik van ‘n spesiaal ontwerpte, deurlopende hoëdruk bioreaktor, om die invloed wat die gestoorde CO2 op die ondergrondse mikrobiese diversiteit en metabolise koolstofsiklus het, te evalueer. As gevolg van die uiterste toestande in die diep ondergrondse omgewing, moet die oorgrote meerderheid van hierdie mikroorganismes groei en oorleef in besondere energie beperkende toestande, wat veroorsaak dat hulle onaktief is, of besondere lae metaboliese aktiwiteite vertoon. Alhoewel hierdie studie aangedui het dat in die meeste van die toestande wat getoets is, die mikroorganismes nie in staat was om te vermeerder nie, of selfs waarneembare hoeveelhede van verwagte metabolise produkte te genereer nie, het hulle verbasend lewensvatbaar gebly. Die mees aanvaarbare verklaring hiervoor is dat die mikroorganismes biofilm gevorm het, wat hulle kon gebruik het as ‘n moontlike beskermingsmeganisme teen die uiterste toestande waaraan hulle blootgestel is. Dit dui uiteindelik daarop dat lewensvatbaarheid moontlik belangriker is as die spesifieke veranderinge in die diversiteit of die biomassa opbrengste, wanneer studies op die ondergrondse koolstofsiklus gedoen word. ‘n Merkbare afname in diversiteit was waarneembaar nadat die bioom blootgestel was aan koolstofbergingstoestande. Slegs groepe vanuit die Bakterieë en die Archaea was in staat om hierdie toestande te oorleef, terwyl geen Eukariote opgespoor kon word nie. Die transkriptoom data, wat verkry is vir die ondergrondse bioom, het aangedui dat geenprodukte van swaelmetabolisme, stikstofmetabolisme, en koolstofmetabolisme teenwoordig was en verskeie ontledings van die bioreaktor het bevestig dat mikroorganismes, wat gebruik maak van hierdie metabolismes, steeds lewensvatbaar was na ses weke onder koolstofbergingstoestande. Hierdie toestande, hoofsaaklik as gevolg van die suuromgewing wat deur die opgeloste CO2 geskep is, veroorsaak dat loging van metale uit die sandsteen, veral aluminium en yster, plaasvind, wat op hul beurt verdere stresvolle toestande veroorsaak en die groei van die ondergrondse bioom nog verder beperk. Dit kan ‘n baie groot invloed uitoefen op die ondergrondse koolstofsiklus en behoort gevolglik oorweeg te word tydens koolstofberging. | af |
| dc.description.sponsorship | South African Centre for Carbon Capture and Storage (SACCCS) | en_ZA |
| dc.description.sponsorship | National Research Foundation (NRF) | en_ZA |
| dc.description.sponsorship | Ernst and Ethel Eriksen Trust | en_ZA |
| dc.description.sponsorship | Technology Innovation Agency (TIA) | en_ZA |
| dc.description.sponsorship | TATA group | en_ZA |
| dc.description.sponsorship | Deep Carbon Observatory (DCO) | en_ZA |
| dc.description.sponsorship | Shimadzu | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/4783 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Climate change | en_ZA |
| dc.subject | Carbon sequestration | en_ZA |
| dc.subject | Geological storage | en_ZA |
| dc.subject | Deep subsurface | en_ZA |
| dc.subject | Metabolic carbon cycling | en_ZA |
| dc.subject | CO2 fixation | en_ZA |
| dc.subject | High pressure bioreactors | en_ZA |
| dc.subject | Aluminium toxicity | en_ZA |
| dc.subject | Thesis (Ph.D. (Microbial, Biochemical and Food Biotechnology))--University of the Free State, 2015 | en_ZA |
| dc.title | Geological carbon sequestration and its influence on subsurface microbial diversity an metabolic carbon cycling | en_ZA |
| dc.type | Thesis | en_ZA |